Gyratory crushers, sometimes called cone crushers, are utilized in many applications for crushing hard material, such as pieces of rock, ore etc. In a gyratory crusher a crushing gap is formed between an outer crushing shell and an inner crushing shell. The inner crushing shell is mounted on a crushing head which is made to gyrate by means of an eccentric. The vertical position of the inner crushing shell relative to the position of the outer crushing shell, and, hence, the width of the crushing gap may be controlled by a hydraulic control system. As the crushing head is gyrated pieces of rock etc. is crushed between the inner and outer crushing shells in the crushing gap.
Occasionally objects that are not easy to crush enter the crushing gap. Such objects, sometimes referred to as tramp material, may cause severe damages to a gyratory crusher. U.S. Pat. No. 4,060,205 discloses a hydraulic accumulator which relieves the pressure in a hydraulic control system when uncrushable objects enter the crushing gap. It has been found, however, that also with the hydraulic accumulator of U.S. Pat. No. 4,060,205 the gyratory crusher may be exposed to very high pressure peaks when uncrushable objects enter the crushing gap.